League One or League 1 may refer to:
Association football
EFL League One, the third tier of football in England.
China League One, the second tier of football in China
K League 1, the top-tier football in South Korea
Lao League 1
League1 British Columbia, semi-professional regional league in Canada
League1 Ontario, semi-professional regional league in Canada
League1 Ontario (women), semi-professional women's regional league in Canada
Scottish League One, the third tier of football in Scotland
Thai League 1, the top tier of football in Thailand
USL League One, a third-tier soccer league in the United States
Rugby
RFL League One, the third tier of rugby league in Europe
National League 1, the third tier of rugby union in England